


A Study in Mutualism

by Escopeta



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Adult Themes, Alternate Universe - Canon Divergence, Angst, Explicit Sexual Content, F/M, Friends With Benefits, Multiple Pov, Other Additional Tags to Be Added, Pre- and Post-Timeskip, Romance, Slice of Life, Slow Burn
Language: English
Status: In-Progress
Published: 2020-11-22
Updated: 2020-11-22
Packaged: 2021-03-09 21:00:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 6,021
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27662375
Author URL: https://archiveofourown.org/users/Escopeta/pseuds/Escopeta
Summary: It was a straightforward arrangement. Her curiosity is satiated, and his lust is satisfied. Casual, no strings attached. Time it right so they don't get caught. Careful to avoid certain types of consequences. She's smart enough to know that, and he's been doing this long enough with others to be cautious during every instance of it.Except these sorts of things are too good to be true, aren't they? There always has to be a catch.The catch being feelings, well, that's just the tip of the iceberg. But maybe they could've avoided this had they noticed sooner. Noticed the growing fondness persisting outside the bedroom as the days rolled by.And holding strong, even years later.
Relationships: Sylvain Jose Gautier/My Unit | Byleth
Comments: 24
Kudos: 70





	1. A Proposition

“How about you, Byleth? Ever been with anyone?”

The question makes her pause as she takes a swig of her pint. When she agreed to go out to the local tavern with Catherine, Shamir, Manuela, and some other female coworkers, she didn’t think she had to talk much. Just nod her head every once in a while, and then maybe form a full sentence if they asked her what she thought of the fresco in the cathedral, or something.

But once they’ve all had a few drinks in them, she quickly realized they were fast to change topics into a more intimate nature. One she doesn’t have anything to share about because that’s not something she’s ever done.

“No,” she replies honestly. Hoping that they drop the subject.

(They don’t.)

“Really? With a body like yours?” another woman says. “That has to be a lie.”

“It’s not. As a mercenary, those things didn’t matter to me. Never been with anyone. Either on a date, or sexually. That’s not something I prioritized.”

“But everyone has needs. And I’m sure even a virgin like yourself would want to—”

“Don’t pressure her,” Manuela says, a slight slur to her tone. “If she doesn’t want a man—or a woman—then she should be free to make that choice.”

She clamps a hand on Byleth’s shoulder, lazily wiggling her finger at her. “Don’t you ever let any man try to trick you into sleeping with him, alright? Otherwise he deserves to have his balls cut off.”

“I’d kill him before he ever got the chance to touch me,” she answers honestly. (Hey, it’s what Jeralt told her she should do if it ever happened.)

Catherine laughs. “Well, whoever you do end up being with—if that’s even something you want—just use your best judgment, alright Byleth?”

It’s not something she cares about, no. But as she falls silent while all the ladies talk of their own experiences, it starts making her curious. Romance, and sex, aren’t things she’s ever really wanted before. Maybe it’s because her emotions were stunted for the longest time and are only just now beginning to reveal themselves to her.

_Is that something I want? Or do I just want to experience it, for knowledge’s sake?_

  
  
  
⟣ ⋯ ⟡ ⋯ ⟢  
  
  
  


As the weeks bleed into the next moon, she can’t get that night out of her mind. Though she wonders if it’s strange for her to ask just anyone to help her out with this. They might laugh at her inexperience, or try to take advantage of the situation—not that she’d let them. But, she always needs to be prepared for the worst.

And so, in the third month of her new teaching position at the Officers Academy, she makes a decision. One that she’s sure will have dire consequences if anyone finds out. But her curiosity has to be satiated. Just reading those erotic novels Manuela lends her isn’t enough. In fact, it only makes her want to experience it even more.

There’s solely one person she feels comfortable asking. Only one she trusts, she’d even say. Because she _knows_ he won’t be uncomfortable with it once he finds out what it is she wants. Considering how he’s always flirting with her, and catching him constantly eyeing her assets if she’s nearby, it’s not hard to put two and two together.

Luckily she finds him in town as she’s making a shopping trip for supplies. He’s arguing with a young woman who then slaps him across the face before she stomps off, tears trickling down her cheeks. Then she disappears into the crowd, pushing past all the hustle and bustle.

Yep. She’s really going to do this, isn’t she? Ask for assistance about her problem… with him.

Her standards must be low.

“What maiden does that make for this month?” Byleth asks as she walks up to him. “The twelfth?”

Sylvain rubs at his cheek where it’s still red and then turns to her. “Oh, you saw that?”

“Unfortunately. You’re a bit of jerk, you know that? Broke that poor girl’s heart.”

“C’mon, Professor!” he whines. “It’s hard on me too! It’s not like I _enjoy_ breaking up with women. I’m actually feeling pretty lousy right about now. If only there was someone to comfort me, and lift my spirits a bit.”

He hangs his head a little, looking at her with puppy eyes. “Professor, it’s okay if you want to console me.” Wow, moves right from one woman to the next. “I actually have some exquisite tea back in my quarters.” He smirks, stepping closer. “We could go back to have some and maybe chat about love.”

“Does your idea of our chat end with me topless?” she asks sarcastically. “Or completely naked on your bed, I’ll bet?”

Sylvain laughs, and grins wider. “Well if you’re offering, I _definitely_ wouldn’t complain.”

Byleth rolls her eyes. “I do want to chat with you, actually, but not over tea, or in your room. It’s more of a serious matter.”

He frowns and says, “If it’s about my training log from last week, I promise I’ll make up those hours before the month is over.”

“No, that’s not it.”

She waves at him to follow her. They walk away from the crowd of the main plaza and take the side streets. They get to a quieter square away from the central markets, and sit down at a bench nestled under the shade of a tree.

Making sure no one is around, she sighs lightly as Sylvain sits beside her. “What I am about to say has to stay between us, indefinitely. Is that clear?”

He leans against the bench as he faces her, one arm hung over the backrest. Giving her a lazy smile, he teases, “If I didn’t know any better, I’d think you were coming onto me. I wouldn’t blame you.”

“That’s not it, but it’s something similar.”

His smile falls, clearly not expecting to be at least partially on track. “Uh… so, what is it you’re…” He stands and glances up at the tree. Actually walks around it to inspect it. But it’s too spindly to obscure anyone or anything of note there. “Am I being pranked or something? Anyone hiding out here?” He returns to the bench, looking at it from every angle before crawling under it. “Setting me up for—”

“Do you want to have sex with me, Sylvain?”

He jerks back and knocks his head on the underside of the bench. Why is he surprised? She knows he’s been thinking about it. Not like it’s a secret he’s attracted to her for shallow reasons.

When she had first met him, a while back when she chose to lead Dimitri’s class of the Blue Lions House, Sylvain had instantly hit on her. Called her an ethereal beauty, and immediately asked if she’d like to privately talk about marriage with him over tea.

That same day at lunch, he was surrounded by several giggling and swooning girls at the dining hall table as he charmed them with his words and carefully timed winks.

Men like him are the kind her father warned her about once upon a time. And in the past, some have even tried to get close to her for one reason, and one reason only. But she had been stoic and unapproachable, mostly unintentionally, but sometimes with the goal of making them leave her alone. (She can’t just kill people she doesn’t like. That’s not ethical.)

Yet in a strange way, that’s why she trusts Sylvain, and only Sylvain, to help her with this problem. A philanderer who’s been lusting after her since day one. Someone like him wouldn’t let this once-in-a-lifetime opportunity easily slip from his fingers, as skeevy as that sounds.

It’s pretty logical, actually. They’d both be doing it for their own gains if he’s agreeable to her terms.

“Professor, is that a rhetorical question?” he asks as he rubs his head, returning to his seat.

“No. I’m being very serious. Because if you do, then I will consent.”

Sylvain looks at her with wide eyes. Casts a glance over his shoulder before he leans forward. “Are you pulling my leg?” he asks quietly. “Because if so, you can just break if off if you want.”

“I know what I’m saying,” she replies just as quietly. “I’ve never had sex before, and I want to experience what it’s like. You’re the only one I’m comfortable asking, but I also know it’s highly inappropriate. Especially since you’re my student.”

“But we’re the same age, aren’t we? I don’t see a problem at all.”

“…It just can’t be known to anyone but us, that’s it. We could both get in severe trouble otherwise. Obviously.”

She explains that, despite her asking this without any feelings attached, she’s still not comfortable asking a complete stranger. Sylvain she knows, at least. And even if he breaks women’s hearts, he doesn’t strike her as a complete scumbag when it comes to sex. Like forcing himself on a woman—which he assures is something he doesn’t do; the thought itself turns him off, looking visibly disgusted as he says it.

“No strings attached,” she informs. “It’s beneficial to us both. I get to experience it, and you get to sleep with me.”

“How many times?” he asks after a pause, sounding a little serious.

Byleth shrugs. “Until we’re satisfied. I doubt one would be enough. I’ve heard there’s lots of ways to be sexually intimate, so… multiple times will be necessary. But if we’re going to do this, then it can’t be back-to-back. We’ll have to time it right so as not to get caught.”

He groans low in his throat. “Do you know what you’re doing to me right now, Professor? Fulfilling one of my many fantasies? I almost want to pinch myself to make sure I’m not dreaming.”

“I figured,” she says lightly. “But that means you better not disappoint, Gautier.”

Sylvain grins. “I won’t. This is obviously important to you, so it’ll be important to me. We’ll start off slow since you’ve never done this before. Just tell me when our first ‘session’ will be.”

“This Friday evening, here in town at the Foothills Inn. To avoid suspicion, we can’t keep going there after that. But at least for our first coupling, it’ll do. Lay out the details and everything.”

“Alright. Friday evening it is.” He gets up, and with that sly smirk of his, says, “You’ve just made my whole year, Professor. I promise you haven’t made a mistake.”

“You better keep that promise, Sylvain. And if we’re to do this, call me ‘Byleth’ when we’re alone.”

He laughs under his breath. “Okay, Byleth. You’ve got a deal.”

**Notes for the Chapter:**

> Hello there! I've been wanting to write a fanfic like this for the longest time now. I'm primarily a Claudeleth shipper (so some of you may know me already from my fics about them), but Sylveth is a close second. There are certain scenarios that I don't find plausible with Claudeleth, but work for Sylveth, and this happens to be one of them. Just based on how I personally see the differences in their relationships.
> 
> I really love Sylvain, so I want to explore his character in this work. I should also mention that when I tagged this as "Canon Divergence", I mean it in the sense that the war doesn't happen. Oh there's still a nefarious plot to be had, but Edelgard isn't involved for once. The Slithers will get more focus here instead.
> 
> Also, heed the other tags. When I wrote "Angst", I meant it. You'll see. Lmao
> 
> This fic isn't done, and won't be done for a long while. But I'm uploading the first chapter for today's prompt of Sylveth Weekend (I'm actually one of the event organizers!), and the second chapter--which is the first smut scene--will be uploaded tomorrow.
> 
> Thanks for reading, and I'll see you all next update! ᕕ( ᐛ )ᕗ


	2. Foothills Inn

On Friday at lunchtime, she sits in the gardens on a bench as she reads over her lesson plan for when class resumes. In the springtime air there wafts the scent of roses. When she had gone to town earlier in the week, all the florists were out of the white variety. This is normal for this time of year, apparently.

She’s never participated in the Garland Moon tradition of weaving the white rose buds together into necklaces or crowns. Sometimes bracelets. They’re for friends and potential lovers—even those who merely have a crush.

In all her life, she has had neither.

Seeing the female students weave them in the gardens at lunch time is interesting as a result. Byleth has never cared much for flowers beyond noticing they’re pretty to look at. Her mother apparently liked them a lot, according to Jeralt. A species of bloom that’s pink and in little clusters instead of a single stem. Valerians they’re called, or something. She’s not quite sure.

Familiar laughter catches her attention, and she looks up toward the nearest hedge. Sylvain is there with several girls around him, each with rose-colored cheeks as they hold a garland in their hand, no doubt wanting to offer it to him.

Some hide it behind their backs, and others are practically shoving it in his face. He takes them all with a smile and says some honey-soaked words that has them blushing like brides. Their satisfied smiles grow wider when he wears them, and wider still when he presents himself in an exaggerated bow as the white buds adorn his person.

When he comes up, he catches Byleth’s line of sight, and gives her a quick wink.

_Are you still going to go through with it?_

Ever since she made that proposition to Sylvain, Sothis has made her opposing opinion on the choice clear nearly every day.

_Yes. I want to know what it feels like._

Her mind companion sighs heavily.

_Should something of consequence occur, do not expect me to coddle you. You will have made your bed, and you will therefore lie in it. And engage in other reclined activities, apparently…._

_We’re both doing it for our own selfish reasons. I’m comfortable with that._

_Then I will put myself to sleep throughout the whole ordeal. I want to know nothing about your experience while it’s occurring._

_Fine by me._

Sylvain walks away with the girls, one on each arm and others following behind and around him like moths to a flame. They venture into the dining hall, and Byleth shakes her head. From observation alone, this week is turning out to be a good one for him. What with all the garlands and feminine attentions he’s received so far.

And the promise of laying with her come the end of the week.

  
  
  
⟣ ⋯ ⟡ ⋯ ⟢  
  
  
  


She arrives at the inn first that Friday. Much earlier than she’s expecting Sylvain. Doesn’t want anyone noticing them and wondering why they’re together in the evening without other students around.

Byleth busies herself reading a book meanwhile. Another borrowed piece of fiction from Manuela’s personal library. She knows the lewd things that happen in this text are most likely exaggerated, but there’s probably some truth in them as well.

When a knock comes at her door, Byleth puts the book away to answer it. She lets Sylvain in quickly who is dressed down in casual wear. Out of his uniform like she asked. Part of his shirt is unbuttoned. 

As she locks the door, she says, “You sure you weren’t followed?”

He smiles at her as he flops down on the bed. “Nope. Pro—Byleth, I’ve been doing this for a long time now. I know how to be elusive when it comes to things like this. Most of the time.”

Sylvain sits up when she begins to remove her boots. “So, what’re the rules?”

“Aside from both of us always needing to consent,” she takes off her belt where her dagger hangs from it, “there aren’t too many. No flirting with me outside of our arrangement, under any circumstance. There’s no need to make people suspicious. Also, no kissing on the mouth or face. Neck and behind the ear is fine, as well as anything lower than that.”

“Fair enough. Can I ask why though?”

Because from what she understands, kissing is something a lot more intimate than sex. There’s a certain connation attached to it, and a bigger emotional response. Apparently. She’s sure she won’t develop feelings for Sylvain since she doesn’t really understand the full breadth of her emotions. But she can’t guarantee he won’t feel something for her down the line. (Although in all honesty, she’d be surprised if anyone did. She can’t see herself as… girlfriend material.)

Not that she’s worried. He doesn’t seem like the type to get severely attached to people, unless they’re his friends. Even so, she needs to be cautious.

“Kissing usually entails an emotional connection. Since this is just a casual thing between us, it’s not necessary to do. I don’t expect a relationship out of this, in case it wasn’t obvious.”

He smiles, an amused huff escaping him. “Of course not. And thanks for saying that. Because as you know,” he starts to take off his boots, “I’m only here to have a good time.”

Byleth sits next to him on the bed and waits for him to be done. Sylvain looks to her, scooting closer. “So, how _new_ , exactly, are you to this?”

“Never had sex before, like I said. Or have even done a sexual act. No one has touched me in any way that wasn’t intended to kill me.” He makes a pained face at that. Maybe not the best thing to say when they’re trying to be physically intimate. “I have no experience whatsoever. The only knowledge I have comes from the erotic novels Manuela lends me.”

Sylvain laughs under his breath. “Well I’ve read plenty of books like those, and they kind of exaggerate things.”

“Yeah, I guessed as much.”

His smile is smaller now as he searches her face. “How about we discover what you like then, Byleth? I could tell you a bunch of things, _but_ , I think it’d be better if you find out for yourself.”

“That’s fine. I still want to experience sex though.”

He grins wide, looking like he almost wants to laugh again. “We’ll get there, even tonight. But what’s the rush?”

Sylvain places a hand on her knee, lightly stroking down her calf. “How about we begin with touches? No one’s ever touched you before in a way that wasn’t to harm you, right? We should change that. You deserve to feel softer things.”

She hums in response, her skin already feeling a little tingly as he slowly runs his hand up her thigh. She’s doesn’t have on her lace stockings this time; they’re a usual signifier of who she is as she wears them often. 

“Thighs are a common erogenous zone,” he tells her.

“What’s that mean?”

“Means places that make someone sexually aroused. I should also mention that if you want me to stop touching you at any point, let me know.”

“Oh I will; don’t worry.”

Sylvain grins slightly, a twinkle to his eyes. “Feel like there’s a kind of threat laced under there, but I guess you wouldn’t be Byleth if there wasn’t.”

He’s slow in running his hand along her thigh. Atop of it, on its side. His fingers brush the hem of her shorts, and he makes a comment about how small they are. That they drive him crazy whenever she wears them because they’re so tiny, and so tight.

“You have fantastic thighs, y’know that?” he compliments, running a hand on each one of them. “When I first saw you, I couldn’t believe a woman like you existed.”

“Why’s that?” she asks, wanting him to slide his hands higher. To go faster.

He moves his hands away to caress her shin, then dip down to brush against her calves again. “Because you have everything. Shapely legs,” he moves higher, “amazing thighs, a pert ass,” and again, “and wide hips. Every time you walk, there’s a tantalizing sway to them that gets me riled up, y’know.”

His hands slide against her exposed belly, flat and toned from her years of training as a mercenary. Then his palms slip up higher, at the edge of her ribs. He looks at her in silent permission and she nods.

Sylvain’s hands move up to curve over her breasts, “And the biggest rack I’ve ever seen,” and Byleth gasps lightly.

The smile on his face falls in surprise for a fraction of a second before it curls on his lips again. “I think we’ve found where you want attention. Take off your shirt for me?”

Byleth does, tossing it on the floor, leaving her in a black lacey bra. Sylvain takes a moment to just stare. “Every time I think you can’t get any more gorgeous…”

“I like lace,” she notes quietly.

“And lace suits you.”

His finger trails up the meticulous pattern along the top edge, and then lightly tugs at her bra strap. Byleth reaches back behind her, not sure why she’s feeling a little hot all of a sudden. From her chest down to her stomach, and starting to simmer even lower than that.

She unhooks her bra, and casts it aside. Her fingers curl at the sheets as his gaze is locked onto her chest. Sylvain thumbs at her ribs, until his hands cup the sides of her breasts. Byleth feels warmer now as he cradles them in his large hands, and hotter still when he groans.

“Fuck, they—they spill over,” he mutters to himself as he fondles them slowly. Kneads the plush mounds as Byleth lightly breathes out of her mouth, eyes fluttering closed.

“You like that,” he says in a low voice. “Not surprised. It’s a common place women like being touched when getting intimate. And I will gladly hold them in my palms all you want. What goes hand in hand with that is…”

A small squeak escapes her when he gently pinches at a nipple, and then the other one.

Byleth closes her legs as she places her hands over his, guiding him as he works at her breasts. Her throat strains in almost a whine, which causes Sylvain to ask, “Something the matter?”

“…You’re going too slow,” she states. “I don’t—I want to go faster. Can’t I just get naked?”

He laughs lightly. “Sure. But I don’t want to be unfair.” Sylvain’s deft fingers make quick work of his shirt buttons. He discards the garment off to the side, then brings her hand against his chest. “You’re allowed to touch too, you know.”

She stares at his torso. Neatly cut into all the muscle groups. She traces a finger down the divide of his pectorals, and lets them linger as she explores the shapes along his abdomen. He’s been taking his training seriously if he’s already this pronounced in signs of physical strength.

But that’s probably not very sexy of her to say. (Then again, she’s not even sure how to be sexy in the first place.)

“Like what you see?” he asks playfully.

She may be awkward at this, but at least she chose someone considerably attractive.

“Yes.”

“Good. I’m not in a rush, but if you’d like to go faster, we can.”

Byleth nods, and then there’s less talking after that. She gives him permission to touch and explore her, noting that she’ll tell him if she doesn’t like something.

But what she does like is feeling his lips on her shoulders, and the nips he gives her across her collarbones. Pecking kisses down the swell of her bountiful breasts. The fleeting licks on her nipple before he starts to lightly mouth at it, then suck, as he tweaks her other one between his pointer finger and thumb.

An airy moan escapes her—the sound so foreign to her ears and her voice that she’s sure she’s imagined it, until he starts to suck on her other pert bud while the wet one hardens, exposed to the air.

He brings her closer as he kisses her shoulder again until he’s moving up along her neck. She’s flush against him, and she trails her hand along his firm chest as his own hands slide down her bare back, fingers slipping past the hem of her shorts.

Byleth takes them off, letting them fall to the floor. It leaves her in her black panties that are… surprisingly wet.

Sylvain grins, and tells her it’s normal. A good sign, because it means she’s getting aroused. Is that why her face starts to heat up when he teases her crotch with two fingers along the black fabric? Why she presses closer when he traces the suggestion of the divide of her lower lips?

When she feels a hardness against her abdomen, she sees he’s reacting much the same from the growing bulge in his trousers.

He stands up to take them off, leaving him in just his smallclothes; a pair of thin shorts. And she can’t help but stare at the bulge, a little surprised that it looks bigger than she assumed. She’s read that’s usually a very good thing for her, but, with no experience under her belt, who is she to definitively agree?

She’s rising to meet him as he brings her into an embrace, his hands resting at the small of her back. He continues kissing her neck again and she angles her head so he can suck lightly on the skin there. He hisses when she curiously palms at his bulge—oh, he must like that. Good to know.

In turn, she likes it when he cups her ass, squeezing the flesh as he flatters her. How firm it is. Nice and plump. His hands slip into the small black panties to knead at her rear, and she rubs herself against his bulge, which makes him groan.

He asks if she’ll take them off, and she complies. Steps away from him just a tad as she lets the last piece of her clothing fall down her legs and meet the small pile on the ground.

There’s hunger in his eyes as he gazes at her from head to toe, and the cool air of the room brushes against her exposed crotch, wetter than it was previously. Heat flares up to her face when he matches her state of undress, removing his shorts, and freeing his erection.

Byleth guides a finger along its length and he shivers as she fits her hand around it. It’s big, and sort of long, although she doesn’t really have a frame of reference for that. But it makes heat coil in her belly as she wonders how deep it’ll go once its inside of her.

She gasps when his fingers play at the plush lips between her legs, groaning about how wet she is already. He brings her against him again, whispering hotly in her ear that he’s going to prepare her with his fingers. The last thing he wants to do is to hurt her during her first time.

“I want it to be memorable for you,” comes his voice in wisps as he sticks the first finger in her folds. “Because so far, it’s becoming memorable to me.”

When he pulls the digit out, it brushes against a bundle of nerves that has her rocking forward ever so slightly. He smirks against the skin of her neck, saying he can’t wait to give that little bud attention with his mouth in the future.

His _mouth_.

“Let’s focus on the present for now, though.”

He sticks two fingers in her this time, slowly scissoring them in her tight heat. Byleth rocks on them in a slow rhythm, until he adds in a third and she gasps into his chest as she tightens her arm around him, the other still slowly stroking his length.

“Bed,” he breathes into her ear. “You’re—goddess, fuck—you’re ready, yeah?”

“Yes,” she says, her voice almost faint.

Sylvain lays her down on her back as her head is supported by the pillow. She keeps her legs spread when he bends over her half-way. Tells her he’s going to start slow as he pushes the tip in her and she gasps more audibly, clutching the softness of the pillow.

He closes his eyes for a second, cursing under his breath at how good it feels the further in he goes. He’s careful, saying he doesn’t want to hurt her. Wants her to get used to the size of him before he even thinks about going faster.

“It’s your first time, and I want you to feel good—oh _fuck_ ,” he groans, “you’re so… _tight_ , Byleth.”

“Is that bad?” she asks breathily as she feels him slide out.

“Not for me, but for you it might be—,” he shivers as he pushes back in, and a semblance of a moan slips past her lips, “—fuck, okay, if it hurts at all, at any point—”

“I know, I know. I’ll— _ah_ —tell you. Please just… just move, Sylvain.”

He smiles at her, looking like he wants to laugh just a smidge. Then he’s sliding back out, and then in again. Byleth feels so full, and almost agonizingly frustrated as he continues his slow rhythm. She knows he doesn’t want to hurt her, but damn. She wants to feel more of him much, much quicker.

Though it _is_ a stretch, yet not quite painful. It’s a sensation that makes her hot again, and that heat starts to spread across her cheeks as she listens to the wet sounds every time his dick moves inside of her. And after a few more experimental thrusts, she says she’s ready.

She wraps her arms around him when instructed as he lays over her front. His firm grip is on her hips as he starts to rock faster, and Byleth hums as the friction gets hotter and hotter. She spreads her fingers out as her hands roam his back, feeling the tightness of his muscles and the blades of his shoulders.

Then she’s asking him to go faster, and he complies. Little sounds she didn’t think she was capable of making start to slip out of her. Voice higher pitched, almost pitiful to her ears. But she can’t help it, just like she can’t help when she starts to buck her hips upward to meet his thrusts.

He groans into her ear as he speeds up, and he goes deeper, eliciting a moan from her that has him shiver, and then move even quicker. Until coherent thought slips away from her and all she feels is the warmth of his body and the strain of her hips as she bucks faster and faster to get him in further, and when she says he can go harder, he does.

It draws out a long moan from her in that high pitch again and then he’s pounding into her. Their skin slapping together as the wet slick sounds get louder and louder and Byleth can’t help it when his name falls out of her mouth over and over. Shivering as he whispers hers in return, some of it lost among the increasingly loud creaking of the bed as they meet the other’s hips.

Then he’s changing the angle and bucking into her deeper and harder and she lulls her head to the side when he starts to kiss her neck again, breath hot on the lobe of her ear and she digs her fingers into his back and he’s lifting her hips off the bed as he pounds and pounds and _pounds_ —

Byleth cries out his name as her back arches and her toes curl, pressing her breasts to his chest. Sylvain groans with his next thrusts until her tight walls squeeze him and then she gasps when she feels something warm shoot into her. It sends a pleasurable shiver down her spine as she plops back onto the sheets, and he finally stops moving.

They both take a minute to breathe. She feels the sweat cooling her skin and his. Gazes at his face when he lifts his head to look at her. Takes in his lazy smile as a bead of perspiration trickles down the corner of his forehead. He lifts up a hand to brush away her sticky bangs.

He’s flaccid inside of her, but doesn’t pull away immediately, and she can’t say that she minds. But she does when he slips his cock out of her folds a moment later. She lays there, her whole body feeling like pudding. Watches him as he goes to the pocket of his trousers and takes out a cloth. He wipes it against her crotch to clean her up, and she hums, words still failing her as she comes down from her high.

Sylvain lays next to her then, pulling her into an embrace against him, nearly chest to chest.

“How was it?” he asks her, still somewhat breathless.

She can only nod as nothing comes out when she tries to say ‘good’. It causes him to laugh when she’s just flapping her lips, and he kisses her shoulder.

“I’ve been wanting that for a while,” he admits. Not that she’s surprised. He’s not exactly subtle when he daydreams in class, or when he’s checking her out.

“Well,” she says after she takes a breath, “how was it for you then?”

“More than I could’ve ever imagined. Better than anyone I’ve ever—,” he shakes his head, bringing her closer, his chin over the top of her head.

She wonders what he was going to say, but decides instead to keep their sticky bodies together to share in the heat that’s starting to evaporate from the room.

When it does, Sylvain pulls the covers over them. Byleth says she didn’t expect to actually stay here, but he reminds she rented it for the night until noon tomorrow.

“Besides, cuddling afterward is one of my favorite parts.” He traces abstract patterns into the skin on her back. “Unless you’re just intending for a quickie, you gotta cuddle after sex.”

“Is that a rule?” she asks, gliding her index finger along the sharp definition of his bicep.

“No, but it’s kind of a shitty thing to just fuck and then skedaddle. I mean, lots of guys do that, but I can’t very well pride myself in pleasing the ladies if I don’t cuddle, right? And, it just feels nice. Don’t you think?”

A hum is what he gets in response.

They keep warm together. Her legs entangle with his, and she can feel his dick against her thigh. It’s soft still, and she wonders what it’ll take to make it hard again. Maybe she’s going too fast but—well, now that she’s finally had sex, she can safely say that she… likes it. At least with Sylvain. She also knows there’s more to experience, so, she’ll savor what she’s gone through so far.

Makes the anticipation for next time that much more oddly satisfying.

“Byleth,” he starts, just before her eyelids start to droop, “I kinda lost myself there. Sorry about that.” When she asks why he’s apologizing, he explains, “I came inside of you. Normally I pull out after I make sure my partner’s finished first, and then I just release on their stomachs, or wherever else they want me to.”

“I liked it when you came inside.” He groans into her ear when she says that, and mutters more to himself that he _has_ to be dreaming now. She almost wants to smile. “It was a little odd since I’ve never felt it, but, that’s something I like, I’ve decided. And you can do it again in the future.”

“You’re really killing me here,” he says with a tone of a laugh. But then he goes silent again, before he says, “I apologized because I’m very careful not to do it. Neither me nor my partner need the trouble of an unplanned pregnancy.”

“…Oh.”

“Yeah, that’s why—well, this is kinda invasive but,” he puts a sliver of distance between them so he can meet her eyes, “do you remember when your last cycle was?”

“Ah, yes,” she admits quietly. “Last week.”

“Hmm. I think… you’ll be okay, but let’s not take our chances.” He tucks a lock of hair behind her ear. “I have some seeds you can eat that’ll, uh, help prevent you ending up with a little bundle of joy after all of this. There’s also a tea you can drink that the seeds are put in…”

Byleth traces the edge of his jaw as he trails off. “We’ll only have our romps then in windows where I can’t get pregnant. Or at least the penetrative kind via your dick.”

“So, are you saying you wanna keep…?”

Nodding, she replies, “Yes. You said you’d give my ‘bud’ attention with your mouth next time, so, it better get spoiled.”

Sylvain grins, tightening his embrace as he shifts them more comfortably side-by-side. “I’m gonna like this year-long arrangement of ours very, _very_ much, Byleth.”

“Me too,” she admits, tracking a hand up his chest. “Me too, Sylvain.”

**Notes for the Chapter:**

> Smut isn't my forte, but I hope this chapter was decent nonetheless. Lol 😅 From what I've written so far, it _seems_ to get better the more sexy scenarios I write. I guess ultimately you readers will be the judge of that when the time comes. Ha ha.
> 
> That's all I can share for now for this fic. I have _most_ of the sex scenes done, but I'm still missing a few. On top of that, I need to add in non-sexual scenes for Sylveth in order for the romantic development to be believable, so... yeah it'll be a while before I can regularly update this story. The majority of the beginning of this work will have smut. The rest of it will be... plot. And angst. With maybe one or two sex scenes along the way. The ending chapters will also have more. (For whatever reason, I can't write smut without writing plot, so, that's that. LOL)
> 
> If you need to contact me for whatever reason, you can check out my Twitter at [pnkpchs](https://twitter.com/pnkpchs) if you'd like! Whenever I make progress on my fics, I usually mention it briefly so people know where I'm at in a particular work. Or you can check out [sylvethlove](https://twitter.com/sylvethlove) which is where the Sylveth Weekend event was hosted! Every now and again, other Sylveth content gets retweeted there, mainly fanart, so if you're starved for content of this ship like I am, it's there if you need it! ;)
> 
> Thanks for reading, and I'll see you all next update! ᕕ( ᐛ )ᕗ


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